The present invention is directed to a colored lamp for emitting colored light of a given range of wavelengths particularly used for both exterior and interior lighting, for luminous advertising, for street lighting, for signal lamps, and for decorations.
Colored lamps up until now have been produced by various means for example by utilizing a gas discharge tube with various fillings and luminous substance, or a second example by either the light source itself or the lamp housing surrounding the light being provided with a colored filter which is only permeable to one part of the light spectrum being emitted by the light source. In the first case or example, the color being emitted is determined by the emission lines of the filling gas and the inorganic luminous substances being used. In the second example, a large part of the light generated by the light source is absorbed and thus is lost.
Specially fabricated fluorescent tubes have often been employed for generating luminous, highly visible signs or other characters. However, such arrangements are structurally extravagant and therefore relatively expensive. A simpler solution is a back lighting of a dark plate with bright transparent characters or a transparent plate having dark characters which provide dark symbols on a bright background. In this method, a large part of the light generated for the background lighting is again lost to absorption.